CA1162014A - Method and apparatus for producing containers from thermoplastic sheet material - Google Patents
Method and apparatus for producing containers from thermoplastic sheet materialInfo
- Publication number
- CA1162014A CA1162014A CA000372766A CA372766A CA1162014A CA 1162014 A CA1162014 A CA 1162014A CA 000372766 A CA000372766 A CA 000372766A CA 372766 A CA372766 A CA 372766A CA 1162014 A CA1162014 A CA 1162014A
- Authority
- CA
- Canada
- Prior art keywords
- sheet material
- molding die
- central portion
- bores
- towards
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000000463 material Substances 0.000 title claims abstract description 45
- 238000000034 method Methods 0.000 title claims abstract description 14
- 229920001169 thermoplastic Polymers 0.000 title claims abstract description 11
- 239000004416 thermosoftening plastic Substances 0.000 title claims abstract description 11
- 238000000465 moulding Methods 0.000 claims abstract description 66
- 238000001816 cooling Methods 0.000 claims abstract description 17
- 230000002093 peripheral effect Effects 0.000 claims abstract description 17
- 239000004033 plastic Substances 0.000 claims abstract description 5
- 239000011248 coating agent Substances 0.000 claims description 13
- 238000000576 coating method Methods 0.000 claims description 13
- 238000013022 venting Methods 0.000 claims description 9
- 238000010438 heat treatment Methods 0.000 claims description 2
- 239000011888 foil Substances 0.000 description 27
- 238000004806 packaging method and process Methods 0.000 description 4
- 238000007789 sealing Methods 0.000 description 2
- 238000007493 shaping process Methods 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 239000011796 hollow space material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000005022 packaging material Substances 0.000 description 1
- 239000002985 plastic film Substances 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 238000009461 vacuum packaging Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C51/00—Shaping by thermoforming, i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor
- B29C51/04—Combined thermoforming and prestretching, e.g. biaxial stretching
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C51/00—Shaping by thermoforming, i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor
- B29C51/26—Component parts, details or accessories; Auxiliary operations
- B29C51/42—Heating or cooling
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C51/00—Shaping by thermoforming, i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor
- B29C51/26—Component parts, details or accessories; Auxiliary operations
- B29C51/42—Heating or cooling
- B29C51/427—Cooling of the material with a fluid blast
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Blow-Moulding Or Thermoforming Of Plastics Or The Like (AREA)
- Moulds For Moulding Plastics Or The Like (AREA)
Abstract
.theta.
METHOD AND APPARATUS FOR PRODUCING CONTAINERS FROM
THERMOPLASTIC SHEET MATERIAL
ABSTRACT OF THE DISCLOSURE
A method of and an apparatus for producing containers from thermoplastic sheet material are disclosed. The sheet material is heated to its plastic state and clamped at its periphery. Then a moulding die is advanced substantially normally towards and against the clamped heated sheet ma-terial. The moulding die has a temperature below the tempe-rature of the heated clamped sheet material and is provided with a projecting peripheral portion and/or a recessed central portion directed towards the sheet material. By further ad-vancing the moulding die by a predetermined amount against the sheet material, this is deformed and shaped into the desired container. A cooling air flow is directed against the clamped heated sheet material in a region thereof adja-cent to the peripheral portion of the moulding die to avoid reduced wall thickness at the edge and corner regions of the container by excessive stretching of the sheet material.
Thus, stable containers of uniform wall thickness may be produced.
METHOD AND APPARATUS FOR PRODUCING CONTAINERS FROM
THERMOPLASTIC SHEET MATERIAL
ABSTRACT OF THE DISCLOSURE
A method of and an apparatus for producing containers from thermoplastic sheet material are disclosed. The sheet material is heated to its plastic state and clamped at its periphery. Then a moulding die is advanced substantially normally towards and against the clamped heated sheet ma-terial. The moulding die has a temperature below the tempe-rature of the heated clamped sheet material and is provided with a projecting peripheral portion and/or a recessed central portion directed towards the sheet material. By further ad-vancing the moulding die by a predetermined amount against the sheet material, this is deformed and shaped into the desired container. A cooling air flow is directed against the clamped heated sheet material in a region thereof adja-cent to the peripheral portion of the moulding die to avoid reduced wall thickness at the edge and corner regions of the container by excessive stretching of the sheet material.
Thus, stable containers of uniform wall thickness may be produced.
Description
BAC~;GR011ND OF T~IE INVENTIONo . _ . . _, .
This invention relates to a method of producing containers, more particularly producing containers from thermoplastic sheet material for packaging purposes. Containers of this kind are especially used for packaging food.
For producing containers of thermoplastic sheet material a molding die is used which is advanced towards and against a heated sheet material which is clamped at its periphery to be in a generally flat state. Conventional molding dies have a raised or projecting peripheral portion and a recessed central portion so that the containers formed thereby will have a recessed bottom. On its bottom side directed towards the sheet material, the molding die has preferably rounded edges, just as on the edge portion of the side walls adjacent the bottom. For shaping the preheated sheet material or foil, the molding die is substantially normally moved towards the sheet material or foil towards a container the shape of which corresponds to the shape of the molding die~ Those portions of the sheet material or foil which are first to contact the molding die are cooled by transmission of heat to the molding die the temperature of which is below the temperature of the plastic state of the thermoplastic sheet material. Thus, those portions not contacting the surface of the molding die at the time a first contact is made will be stretched more than other portions. The stretching effect will be maximum at the edges, particularly at any corners to be formed in the container. The edge ar.d corner portions of the containers are thus formed with reduced thickness, and this is undesirable in view of producing stable containers.
This invention relates to a method of producing containers, more particularly producing containers from thermoplastic sheet material for packaging purposes. Containers of this kind are especially used for packaging food.
For producing containers of thermoplastic sheet material a molding die is used which is advanced towards and against a heated sheet material which is clamped at its periphery to be in a generally flat state. Conventional molding dies have a raised or projecting peripheral portion and a recessed central portion so that the containers formed thereby will have a recessed bottom. On its bottom side directed towards the sheet material, the molding die has preferably rounded edges, just as on the edge portion of the side walls adjacent the bottom. For shaping the preheated sheet material or foil, the molding die is substantially normally moved towards the sheet material or foil towards a container the shape of which corresponds to the shape of the molding die~ Those portions of the sheet material or foil which are first to contact the molding die are cooled by transmission of heat to the molding die the temperature of which is below the temperature of the plastic state of the thermoplastic sheet material. Thus, those portions not contacting the surface of the molding die at the time a first contact is made will be stretched more than other portions. The stretching effect will be maximum at the edges, particularly at any corners to be formed in the container. The edge ar.d corner portions of the containers are thus formed with reduced thickness, and this is undesirable in view of producing stable containers.
2 --OBJECTS OF THE INVENTION:
. . . -A primary object of the invention is to provide a method and an apparatus for producing containersfrcmthermo-plastic sheet material which are substantially free from undesirably stretched and thinned wall portions.
A further ob~ect of the invention is to provide a method and an apparatus for producing containers from thermo-plastic sheet material having an improved rigidity.
A further object of the invention is to provide a method and an apparatus for producing containers from thermo-plastic sheet material using a molding die, the containers having edge and corner portions of appropriate thickness to achieve satisfactory rigidity.
A further object of the invention is to provide a method and an apparatus for producing containers from thermo-plastic sheet material which have a substantially uniform wall thickness, not only in the side walls but also in the edge and corner portions.
SUMMARY OF THE INVENTION:
In accordance with the invention, containers are produced from a thermoplastic sheet material which is heated to its plastic state. The heated sheet material is clamped at its periphery, and a moldig die is advanced against the sheet material for shaping of the same into containers.
The molding die has a projecting peripheral portion and/ora recessed central portion directed towards the sheet material. In order to prevent undue stretching of the sheet material in the edge and corner portions of the container ~6~
to be formed, a cooling air flow is directed against the sheet material at the region thereof adjacent to the peripheral p~rtion of the molding die, i.e. adjacent the corner and edge portions to be formed.
The invention provides an apparatus for performing the method, having a molding die of the above mentioned type and being provided with cooling air flow channels or bores through which the cooling air flow may be directed against the appropriate regions of the sheet mat~rial. In addition, the molding die is provided with a venting channel centrally displaced from the cooling air flow channels to draw the cooling air towards the center portion of the bottom of the molding die and finally vent the air to the environment.
In a preferred embodiment, the contacting surface of the molding die is provided with a coating of felt material, and this coating is provided with openings at the locations corresponding to those of the different channels and bores of the molding die.
DESCRIPTION_OF PREFERRED EMBODIMENTS:
Further advantageous features and objects of the invention will stand out from the following description of examplary embodiments with reference to the drawings, wherein:
Figure 1 is a schematic perspective view of a packag-ing machine in which the method is performed;
Figure 2 is a cross-section of a molding station in the packaging machine of Figure 1, having a device for per-forming the method;
Figure 3 is a perspective view of a molding die and a container molded thereby;
Figure 4 shows a sectional view similar to Figure 2, but of another embodiment;
Figure 5 shows a molding die provided for the embodiment of Figure 4; and ii Figure 6 shows a sectional view of the embodiment of 1' Figure 5 and is seen on the sheet illustrating Figure l. i Referring to Figure 1, a vacuum packaging machine 1 , 10 has in succession a molding station 2, a sealing station 3 ;
and a separating station 4 mounted on a machir,e frame (not shown~.
In the forming station 2, containers 7 are formed of a packaging material foil or sheet material 6 drawn from a roll 5 of stock material. The containers are then filled and closed by a cover foil in the sealing station. In the separating station, the individual interconnected packages are separated from each other.
Figure 2 shows the molding station 2 schematically indicated at Figure 1 in cross-section. It has an upper portion 8 secured on the machine frame (not shown) and a lower portion 11 connected with the machine frame and movable with respect to the upper portion in direction of arrow 100 The lower portion 11 has an inner space 12 into which molding inserts 13 are inserted, in accordance with the shape of the containers to be formed. The inner space 12 is connected with a vacuum pump through bores 14, 15 provided in the molding inserts of the containers to be formed, particularly at the edge regions and corners, and through connections 16, 17 leading towards the vacuum pumps.
"~ 5 ~ , .
, `~ 2~
The u~per portion is provided with a molding die 18 which may be reciprocated up and down into the inner space 12 of the lower portion and into a retracted position remote therefrom, by a piston cylinder device 20 connected with a casing 19 of the upper portion. As may be best seen from Figure 3, the molding die has a central portion 21 at its bottom and a peripheral portion 22 raised over or projecting from the central portion. The peripheral portion has the dimension of the shape to be formed by the molding die in a deep-drawing operation. The central portion 21 is recessed with respect to the peripheral portion by an amount sufficient that the foil or shee~ material will not contact the surface of the molding die in this region, during the molding operation.
In the central portion, particularly in the corners thereof, bores 23, 24, 25, 26 are provided which, as seen from Figure 2, are connected with a pressurized air source ~not shown) through connecting members 27, 28 provided at the top side of the molding die. Centrally of the central portion 21, a venting bore 29 is provided in the molding die.
The connecting members 27, 28 are free to be receiprocated through openings 30, 31 in the casing, and the air escaping through the venting bore 21 may escape to the environment through these openings.
In Figure 3, the bores 23 through 26 are provided near the corners 32, 33, 34, 35. Preferably, as shown in Figure 2, they are arranged in the corners and as close as possible to the inner edge 36 surrounding the central portion 21.
As may be seer, in the representation of Figure 2, the outer dimensions of the molding die 18 are somewhat smaller than the dimensions of the hollow space defined by the molding insert 13 and the side walls.
The device operates as follows: The lower portion 11 is first moved by the piston cylinder device 9 down-wardly so that a container formed in the preceding operating cycle will be moved out of the molding station. Simultaneously, a new heated and not yet shaped foil portion 37 is introduced into the molding station. The molding die is in its retracted position so that it will not contact the foil portion 37.
Subsequently, the lower portion 11 will be moved by the piston cylinder device 9 into the closed position shown in Figure 2 towards the upper portion, clamping the foil portion 37 at its four sides between the upper and lower portions. During a preceding operating cycle in another part of the molding station, or in an individual heating station, the foil portion 37 had been preheated to its temperature for plastic deform-ability. After clamping of the foil or sheet material, the molding die 18 is moved by the piston cylinder device 20 in the direction of arrow 38 towards the foil and against the same into the lower portion 11. The molding die 18 will first contact the preheated foil through its peripheral portion 22. The molding die may e.g. be formed of laminated cloth such as sold under the trade name FERROCELL. By contact-ing the molding die, the portions in contact therewith will immediately transmit heat thereto. As a result, these ZGnes which are somewhat cooled will be less deformed than those over the recessed central portion 21. Vpon further pushing ,~ :
the molding die downwardly, those cooled portions will be less stretched, and a particularly heavy stretching of the foil would result over the central portion immediately adjacent the corners 32, 33, 3~, 35. In accordance with the invention, when the molding die 18 is pushed down, an air stream is directed against the foil in the corners of the central portion, through the bores 23, 2~, 25, 26. This air will flow from the corners towards the center of the central portion and escapes through the ventinq bore 29. Thus, the 10 foil will be cooled across the central portion adjacent the portion thereof already cooled by contacting the molding die.
The limit between the cooled foil and the heated foil which would otherwise be marked, will now be more continuous.
The cooling will be maximum in the corners of the central portion themselves. It decreases towards the center of the central surface. As a result, upon further advancement of the molding die into the lower portion into the end position, although most of the stretching of the foil will occur in the central region, the corner portions (which would be subject to heavy stretching without cooling) will not be stretched more than the other regions, due to the maximum cooling. The temperature of the supplied air and the pressure thereof are adjusted in such a manner that the cooling will be performed to such an extent that the corners will have the same wall thickness as the wall portions of the containers.
When the molding die is moved to its end position in the lower portion, the deep-drawn foil portion 37 is almost applied against the molding insert 13, but it will have somewhat smaller dimensions than the final shape. To this end, by actuating a vacuum pump and generating a vacuum 6Z~
through the connections 16, 17 and the bores 15, 14, the foil will be sucked to the walls of the lower portion to assume the final dimensions. Then, the container will have an essentially stable shape. The molding die will be retracted into the upper portion. Subsequently, the lower portion will be moved downwardly, and the next operating cycle may be begin.
In the embodiment of Figures 4 and 5, those features similar to the above enclosed embodiments are indicated by the same numerals. The embodiment of Figures 4 and 5 differs from the above disclosed embodiment by the fact that the ends of the bores 23, 24, 25, 26 are displaced from the central zone 21 towards the corners 39, 40, 41, 42 of the molding die 18 so that they lie between the corners 32, 33, 34, 35 of the central portion 21 and the above mentioned corners of the molding die, as best seen in Figure 5. Further, the surface directed towards the foil portion 37 is covered with a felt coating 43. The shape of the felt coating 43 is adapted to the outer shape of the molding die. In the embodiment of Figures 4 and 5, the felt coating 43 is provided with open-ings 44, 45, 46, 47 at locations corresponding to the bores 23 through 26, so that the air supplied through the connecting members and the bores may escape from the felt. Further, the felt coating 43 is provided with an opening 48 at a location corresponding to the venting bore 29 so that the air is free to escape from the central portion towards the environment through the ventir-g bore 29.
The operation of the device for deep-drawing a foil is the same as disclosed above. The air escaping from the holes 44 thxough 47 will even come closer to the corners 39 through 42 of the molding die 18 than with the previously described embodiment, and will pass between the felt coatirlg 43 and the foil portion and arrive at the central portion 21 to escape through opening 48 and the venting bore 29. This will result in having a progressive cooling of the progressively deep-drawn foil from the corners towards the central portion.
As soon as the foil arrives in the corners, it will be cooled to such an extent that the stretching thereof will nct be stronger than in other regions. The felt coating will, on the one hand, prevent the foil from being damaged when pass-ing over the outlet openings 44 through 47 and, on the other hand, provide a certain distribution of the introduced air by the porosity of the felt.
In Figure 6, only the lower part of the molding die 18 is shown in cross-section similar to Figure 4. The molding die 18 corresponds to the embodiment of Figures 4 and 5. Only the felt coating 43' differs fronl the previously described felt coating or covering by the fact that no openings 44 through 47 are provided. The air supplied through the bores 23 to 26 will be fed under pressure through the felt cover.
Thus, the air will not locally escape from the bores 23 through 26, but rather escape through surface regions from the felt cover. Just as with the previously disclosed embodi-ment, the air will flow towards the central portion 21 andescape through the opening 48 and the venting bore 29 to the environment.
In the above disclosed embodiment, the cover or coating 43 is made of felt. The thickness of the felt is selected in such a manner that the felt cover will be sufficiently stable ~6;Z~
and that, on the other hand, the air may sufficiently pass therethrough and be distributed in such a manner that the corner portions are sufficiently cooled.For example, the felt cover may be attached to the molding die by an adhesive.
Instead of a felt material the cover or coating may be formed of another material having similar properties.
It should be understood that the present invention is in no way limited to the above disclosed embodiments and that many modifications and improvements may brought thereto without departing from the true spirit of the invention.
`` - 11 -
. . . -A primary object of the invention is to provide a method and an apparatus for producing containersfrcmthermo-plastic sheet material which are substantially free from undesirably stretched and thinned wall portions.
A further ob~ect of the invention is to provide a method and an apparatus for producing containers from thermo-plastic sheet material having an improved rigidity.
A further object of the invention is to provide a method and an apparatus for producing containers from thermo-plastic sheet material using a molding die, the containers having edge and corner portions of appropriate thickness to achieve satisfactory rigidity.
A further object of the invention is to provide a method and an apparatus for producing containers from thermo-plastic sheet material which have a substantially uniform wall thickness, not only in the side walls but also in the edge and corner portions.
SUMMARY OF THE INVENTION:
In accordance with the invention, containers are produced from a thermoplastic sheet material which is heated to its plastic state. The heated sheet material is clamped at its periphery, and a moldig die is advanced against the sheet material for shaping of the same into containers.
The molding die has a projecting peripheral portion and/ora recessed central portion directed towards the sheet material. In order to prevent undue stretching of the sheet material in the edge and corner portions of the container ~6~
to be formed, a cooling air flow is directed against the sheet material at the region thereof adjacent to the peripheral p~rtion of the molding die, i.e. adjacent the corner and edge portions to be formed.
The invention provides an apparatus for performing the method, having a molding die of the above mentioned type and being provided with cooling air flow channels or bores through which the cooling air flow may be directed against the appropriate regions of the sheet mat~rial. In addition, the molding die is provided with a venting channel centrally displaced from the cooling air flow channels to draw the cooling air towards the center portion of the bottom of the molding die and finally vent the air to the environment.
In a preferred embodiment, the contacting surface of the molding die is provided with a coating of felt material, and this coating is provided with openings at the locations corresponding to those of the different channels and bores of the molding die.
DESCRIPTION_OF PREFERRED EMBODIMENTS:
Further advantageous features and objects of the invention will stand out from the following description of examplary embodiments with reference to the drawings, wherein:
Figure 1 is a schematic perspective view of a packag-ing machine in which the method is performed;
Figure 2 is a cross-section of a molding station in the packaging machine of Figure 1, having a device for per-forming the method;
Figure 3 is a perspective view of a molding die and a container molded thereby;
Figure 4 shows a sectional view similar to Figure 2, but of another embodiment;
Figure 5 shows a molding die provided for the embodiment of Figure 4; and ii Figure 6 shows a sectional view of the embodiment of 1' Figure 5 and is seen on the sheet illustrating Figure l. i Referring to Figure 1, a vacuum packaging machine 1 , 10 has in succession a molding station 2, a sealing station 3 ;
and a separating station 4 mounted on a machir,e frame (not shown~.
In the forming station 2, containers 7 are formed of a packaging material foil or sheet material 6 drawn from a roll 5 of stock material. The containers are then filled and closed by a cover foil in the sealing station. In the separating station, the individual interconnected packages are separated from each other.
Figure 2 shows the molding station 2 schematically indicated at Figure 1 in cross-section. It has an upper portion 8 secured on the machine frame (not shown) and a lower portion 11 connected with the machine frame and movable with respect to the upper portion in direction of arrow 100 The lower portion 11 has an inner space 12 into which molding inserts 13 are inserted, in accordance with the shape of the containers to be formed. The inner space 12 is connected with a vacuum pump through bores 14, 15 provided in the molding inserts of the containers to be formed, particularly at the edge regions and corners, and through connections 16, 17 leading towards the vacuum pumps.
"~ 5 ~ , .
, `~ 2~
The u~per portion is provided with a molding die 18 which may be reciprocated up and down into the inner space 12 of the lower portion and into a retracted position remote therefrom, by a piston cylinder device 20 connected with a casing 19 of the upper portion. As may be best seen from Figure 3, the molding die has a central portion 21 at its bottom and a peripheral portion 22 raised over or projecting from the central portion. The peripheral portion has the dimension of the shape to be formed by the molding die in a deep-drawing operation. The central portion 21 is recessed with respect to the peripheral portion by an amount sufficient that the foil or shee~ material will not contact the surface of the molding die in this region, during the molding operation.
In the central portion, particularly in the corners thereof, bores 23, 24, 25, 26 are provided which, as seen from Figure 2, are connected with a pressurized air source ~not shown) through connecting members 27, 28 provided at the top side of the molding die. Centrally of the central portion 21, a venting bore 29 is provided in the molding die.
The connecting members 27, 28 are free to be receiprocated through openings 30, 31 in the casing, and the air escaping through the venting bore 21 may escape to the environment through these openings.
In Figure 3, the bores 23 through 26 are provided near the corners 32, 33, 34, 35. Preferably, as shown in Figure 2, they are arranged in the corners and as close as possible to the inner edge 36 surrounding the central portion 21.
As may be seer, in the representation of Figure 2, the outer dimensions of the molding die 18 are somewhat smaller than the dimensions of the hollow space defined by the molding insert 13 and the side walls.
The device operates as follows: The lower portion 11 is first moved by the piston cylinder device 9 down-wardly so that a container formed in the preceding operating cycle will be moved out of the molding station. Simultaneously, a new heated and not yet shaped foil portion 37 is introduced into the molding station. The molding die is in its retracted position so that it will not contact the foil portion 37.
Subsequently, the lower portion 11 will be moved by the piston cylinder device 9 into the closed position shown in Figure 2 towards the upper portion, clamping the foil portion 37 at its four sides between the upper and lower portions. During a preceding operating cycle in another part of the molding station, or in an individual heating station, the foil portion 37 had been preheated to its temperature for plastic deform-ability. After clamping of the foil or sheet material, the molding die 18 is moved by the piston cylinder device 20 in the direction of arrow 38 towards the foil and against the same into the lower portion 11. The molding die 18 will first contact the preheated foil through its peripheral portion 22. The molding die may e.g. be formed of laminated cloth such as sold under the trade name FERROCELL. By contact-ing the molding die, the portions in contact therewith will immediately transmit heat thereto. As a result, these ZGnes which are somewhat cooled will be less deformed than those over the recessed central portion 21. Vpon further pushing ,~ :
the molding die downwardly, those cooled portions will be less stretched, and a particularly heavy stretching of the foil would result over the central portion immediately adjacent the corners 32, 33, 3~, 35. In accordance with the invention, when the molding die 18 is pushed down, an air stream is directed against the foil in the corners of the central portion, through the bores 23, 2~, 25, 26. This air will flow from the corners towards the center of the central portion and escapes through the ventinq bore 29. Thus, the 10 foil will be cooled across the central portion adjacent the portion thereof already cooled by contacting the molding die.
The limit between the cooled foil and the heated foil which would otherwise be marked, will now be more continuous.
The cooling will be maximum in the corners of the central portion themselves. It decreases towards the center of the central surface. As a result, upon further advancement of the molding die into the lower portion into the end position, although most of the stretching of the foil will occur in the central region, the corner portions (which would be subject to heavy stretching without cooling) will not be stretched more than the other regions, due to the maximum cooling. The temperature of the supplied air and the pressure thereof are adjusted in such a manner that the cooling will be performed to such an extent that the corners will have the same wall thickness as the wall portions of the containers.
When the molding die is moved to its end position in the lower portion, the deep-drawn foil portion 37 is almost applied against the molding insert 13, but it will have somewhat smaller dimensions than the final shape. To this end, by actuating a vacuum pump and generating a vacuum 6Z~
through the connections 16, 17 and the bores 15, 14, the foil will be sucked to the walls of the lower portion to assume the final dimensions. Then, the container will have an essentially stable shape. The molding die will be retracted into the upper portion. Subsequently, the lower portion will be moved downwardly, and the next operating cycle may be begin.
In the embodiment of Figures 4 and 5, those features similar to the above enclosed embodiments are indicated by the same numerals. The embodiment of Figures 4 and 5 differs from the above disclosed embodiment by the fact that the ends of the bores 23, 24, 25, 26 are displaced from the central zone 21 towards the corners 39, 40, 41, 42 of the molding die 18 so that they lie between the corners 32, 33, 34, 35 of the central portion 21 and the above mentioned corners of the molding die, as best seen in Figure 5. Further, the surface directed towards the foil portion 37 is covered with a felt coating 43. The shape of the felt coating 43 is adapted to the outer shape of the molding die. In the embodiment of Figures 4 and 5, the felt coating 43 is provided with open-ings 44, 45, 46, 47 at locations corresponding to the bores 23 through 26, so that the air supplied through the connecting members and the bores may escape from the felt. Further, the felt coating 43 is provided with an opening 48 at a location corresponding to the venting bore 29 so that the air is free to escape from the central portion towards the environment through the ventir-g bore 29.
The operation of the device for deep-drawing a foil is the same as disclosed above. The air escaping from the holes 44 thxough 47 will even come closer to the corners 39 through 42 of the molding die 18 than with the previously described embodiment, and will pass between the felt coatirlg 43 and the foil portion and arrive at the central portion 21 to escape through opening 48 and the venting bore 29. This will result in having a progressive cooling of the progressively deep-drawn foil from the corners towards the central portion.
As soon as the foil arrives in the corners, it will be cooled to such an extent that the stretching thereof will nct be stronger than in other regions. The felt coating will, on the one hand, prevent the foil from being damaged when pass-ing over the outlet openings 44 through 47 and, on the other hand, provide a certain distribution of the introduced air by the porosity of the felt.
In Figure 6, only the lower part of the molding die 18 is shown in cross-section similar to Figure 4. The molding die 18 corresponds to the embodiment of Figures 4 and 5. Only the felt coating 43' differs fronl the previously described felt coating or covering by the fact that no openings 44 through 47 are provided. The air supplied through the bores 23 to 26 will be fed under pressure through the felt cover.
Thus, the air will not locally escape from the bores 23 through 26, but rather escape through surface regions from the felt cover. Just as with the previously disclosed embodi-ment, the air will flow towards the central portion 21 andescape through the opening 48 and the venting bore 29 to the environment.
In the above disclosed embodiment, the cover or coating 43 is made of felt. The thickness of the felt is selected in such a manner that the felt cover will be sufficiently stable ~6;Z~
and that, on the other hand, the air may sufficiently pass therethrough and be distributed in such a manner that the corner portions are sufficiently cooled.For example, the felt cover may be attached to the molding die by an adhesive.
Instead of a felt material the cover or coating may be formed of another material having similar properties.
It should be understood that the present invention is in no way limited to the above disclosed embodiments and that many modifications and improvements may brought thereto without departing from the true spirit of the invention.
`` - 11 -
Claims (7)
1. A method of producing containers having corner portions from thermoplastic sheet material, comprising the steps of:
heating said sheet material to its plastic state;
clamping said heated sheet material on at least two opposed sides thereof;
advancing a molding die substantially normally towards said clamped heated sheet material, said molding die having a temperature below the temperature of said heated clamped sheet material and presenting a projecting peripheral portion and/or a recessed central portion directed towards said sheet material;
deforming said clamped heated sheet material by further advancing said molding die by a predetermined amount to form said container; and during said deforming directing a stream of cooling air flow from said peripheral portions of said molding die towards the inner region of said central portion against said corner portions of said containers to be formed.
heating said sheet material to its plastic state;
clamping said heated sheet material on at least two opposed sides thereof;
advancing a molding die substantially normally towards said clamped heated sheet material, said molding die having a temperature below the temperature of said heated clamped sheet material and presenting a projecting peripheral portion and/or a recessed central portion directed towards said sheet material;
deforming said clamped heated sheet material by further advancing said molding die by a predetermined amount to form said container; and during said deforming directing a stream of cooling air flow from said peripheral portions of said molding die towards the inner region of said central portion against said corner portions of said containers to be formed.
2. The method of claim 1, wherein said cooling air flow is directed from corner portions of said peripheral portion towards said central portion and is then carried off from said central portion by a venting bore in said central portion in said molding die.
3. A device for producing containers having corner portions according to the method of claim 1, comprising a molding die having a projecting peripheral portion and/or a recessed central portion directed, in use, towards said sheet material, said molding die being provided with first bores arranged between a zone of said central portion adjacent to said peripheral portion and the outer corners of said peri-pheral portion and connectable with a cooling air source for directing a cooling air flow against said corner portions of said containers to be formed and second bores displaced from said first bores in a direction towards said central portion for venting said cooling air delivered from said first bores.
4. The device of claim 3, wherein that surface of the molding die which is to be brought into contact with said sheet material has a coating of felt material.
5. The device of claim 4, wherein said coating of felt material is provided with openings corresponding to said first and/or second bores for allowing exiting and/or venting of said cooling air.
6. The device of claim 4 or 5, wherein said first bores are provided in a zone between corner portions of said central portion and outer corners of said peripheral portion.
7. The device of claim 3, wherein said first bores are provided in a zone of said central portion adjacent to said peripheral portion.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19808007086U DE8007086U1 (en) | 1980-03-14 | 1980-03-14 | DEVICE FOR MOLDING CONTAINERS FROM A FILM |
DEG8007086.6 | 1980-03-14 |
Publications (1)
Publication Number | Publication Date |
---|---|
CA1162014A true CA1162014A (en) | 1984-02-14 |
Family
ID=6713788
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA000372766A Expired CA1162014A (en) | 1980-03-14 | 1981-03-11 | Method and apparatus for producing containers from thermoplastic sheet material |
Country Status (8)
Country | Link |
---|---|
US (2) | US4397804A (en) |
JP (1) | JPS56146715A (en) |
AT (1) | AT383987B (en) |
CA (1) | CA1162014A (en) |
CH (1) | CH651797A5 (en) |
DE (1) | DE8007086U1 (en) |
FR (1) | FR2477948B1 (en) |
IT (1) | IT1146706B (en) |
Families Citing this family (29)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4500277A (en) * | 1982-03-02 | 1985-02-19 | W. R. Grace Australia Limited | Apparatus for thermoforming thermoplastic sheet materials |
DE3413714A1 (en) * | 1984-04-12 | 1985-10-24 | Enzler + Co, 8873 Ichenhausen | METHOD AND DEVICE FOR PRODUCING A TUBULAR SHAPED BODY FROM PLASTIC |
IT1202081B (en) * | 1985-01-25 | 1989-02-02 | Nespak Spa | DEVICE PARTICULARLY SUITABLE FOR THE INTERNAL EMBOSSING OF TRAYS OBTAINED FROM FOAM OF PLASTIC MATERIAL EXPANDED BY CONTINUOUS THERMOFORMING MACHINES |
CH673603A5 (en) * | 1987-09-22 | 1990-03-30 | Alusuisse | Press blowing super-plastically deformable metal sheet - using cooling nozzle to decrease metal expansion in areas to be most highly deformed |
US4878826A (en) * | 1987-12-07 | 1989-11-07 | Wendt Michael L | Apparatus for thermoforming plastic materials |
US5162124A (en) * | 1990-03-19 | 1992-11-10 | Illinois Tool Works Inc. | Die system for thermoforming thermoformable sheet material |
US5262181A (en) * | 1990-05-14 | 1993-11-16 | Erca Holding | Apparatus for forming hollow articles in thermoplastic material |
DE4019632C2 (en) * | 1990-06-20 | 1996-12-19 | Tetra Pak Gmbh | Device for heating plate-shaped parts made of thermoformed plastic |
US5622719A (en) * | 1993-09-10 | 1997-04-22 | Fuisz Technologies Ltd. | Process and apparatus for making rapidly dissolving dosage units and product therefrom |
US6146124A (en) * | 1996-06-25 | 2000-11-14 | Thermogenesis Corp. | Freezing and thawing bag, mold, apparatus and method |
US6808675B1 (en) | 1996-06-25 | 2004-10-26 | Thermogenesis Corp. | Freezing and thawing bag, mold, apparatus and method |
DE19632149C1 (en) * | 1996-08-09 | 1998-02-05 | Sekurit Saint Gobain Deutsch | Form stamp for re-forming a profile strand extruded onto an object |
US6696007B1 (en) * | 1996-11-22 | 2004-02-24 | Innovative Automation, Inc. | Mold and process for producing drumhead membranes |
DE19706797A1 (en) * | 1997-02-20 | 1998-08-27 | Kourtoglou Sa | Process for the production of plastic packaging containers and molding station for a plastic packaging container, packaging machine and plastic packaging container, in particular manufactured according to the aforementioned method, and process for the production of filled and closed packaging containers |
ITBO20010020A1 (en) * | 2001-01-19 | 2002-07-19 | Comi Srl | THERMOFORMED ELEMENTS DEVICE AND COOLING METHOD |
US7019819B2 (en) | 2002-11-13 | 2006-03-28 | Molecular Imprints, Inc. | Chucking system for modulating shapes of substrates |
US7641840B2 (en) * | 2002-11-13 | 2010-01-05 | Molecular Imprints, Inc. | Method for expelling gas positioned between a substrate and a mold |
US7090716B2 (en) * | 2003-10-02 | 2006-08-15 | Molecular Imprints, Inc. | Single phase fluid imprint lithography method |
US7316554B2 (en) * | 2005-09-21 | 2008-01-08 | Molecular Imprints, Inc. | System to control an atmosphere between a body and a substrate |
DE102006011159A1 (en) * | 2006-03-10 | 2007-09-13 | Benecke-Kaliko Ag | Process for producing a thermoplastic film |
EP2001602B1 (en) * | 2006-04-03 | 2011-06-22 | Molecular Imprints, Inc. | Lithography imprinting system |
US8215946B2 (en) | 2006-05-18 | 2012-07-10 | Molecular Imprints, Inc. | Imprint lithography system and method |
US7985062B2 (en) * | 2007-07-09 | 2011-07-26 | Benjamin Chesney | Apparatus and process for two-sided thermoforming |
US8814556B2 (en) * | 2007-09-28 | 2014-08-26 | Toray Industries, Inc | Method and device for manufacturing sheet having fine shape transferred thereon |
US20100096764A1 (en) * | 2008-10-20 | 2010-04-22 | Molecular Imprints, Inc. | Gas Environment for Imprint Lithography |
DE102008052599A1 (en) * | 2008-10-21 | 2010-04-22 | Multivac Sepp Haggenmüller Gmbh & Co. Kg | Method for producing a packaging and packaging machine |
DE102009020892A1 (en) * | 2009-05-13 | 2011-02-10 | Multivac Sepp Haggenmüller Gmbh & Co. Kg | Packaging machine and method for closing containers with lids |
GB2474366B (en) * | 2009-10-12 | 2012-11-14 | Stretchform Associates Ltd | Zone cooling |
ES2577832T3 (en) * | 2013-02-20 | 2016-07-19 | Multivac Sepp Haggenmüller Se & Co. Kg | Deep drawing machine with lifting equipment and a procedure |
Family Cites Families (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2444420A (en) * | 1944-12-23 | 1948-07-06 | Gustave W Borkland | Drawing and tempering plastic material |
FR1238405A (en) * | 1959-07-01 | 1960-08-12 | Manducher & Cie E | Improvement in the stamping-forming process of thermoplastic sheets and stamping machine for the implementation of the improved process |
US3121767A (en) * | 1961-05-10 | 1964-02-18 | Illinois Tool Works | Method and apparatus for fabricating sheet formed molded articles |
US3482281A (en) * | 1966-08-23 | 1969-12-09 | Alfons W Thiel | Apparatus for making thin-walled plastic articles |
US3619862A (en) * | 1968-12-23 | 1971-11-16 | Monsanto Co | Thermoforming plug assembly |
US3966860A (en) * | 1969-09-24 | 1976-06-29 | Phillips Petroleum Company | Process for using a contoured assist plug for thermoforming oriented articles |
DE2252219B2 (en) * | 1972-10-25 | 1978-02-16 | Bellaplast Gmbh, 6200 Wiesbaden | METHOD AND DEVICE FOR PRODUCING THIN-WALLED MOLDINGS FROM THERMOPLASTIC PLASTIC |
US4025275A (en) * | 1973-01-31 | 1977-05-24 | Maurice Paul Gournelle | Apparatus for the production of containers and objects made of thermoplastic materials, carrying printed motifs |
US4112042A (en) * | 1973-10-12 | 1978-09-05 | Plastona (John Waddington) Ltd. | Moulding of synthetic plastics sheet material |
US3928523A (en) * | 1973-12-26 | 1975-12-23 | Peter Ward | Moulding of synthetic plastics sheet material |
US4039271A (en) * | 1975-01-07 | 1977-08-02 | Phillips Petroleum Company | Contoured assist plug for thermoforming oriented articles |
US4155697A (en) * | 1976-11-29 | 1979-05-22 | International Paper Company | Container for storing food and process and apparatus for making that container |
US4234536A (en) * | 1978-09-27 | 1980-11-18 | Thiel Alfons W | Method for the manufacture of thin-walled shaped articles of crystalline thermoplastic material |
US4381278A (en) * | 1978-12-11 | 1983-04-26 | James River-Dixie/Northern, Inc. | Method for forming a coated paperboard container |
-
1980
- 1980-03-14 DE DE19808007086U patent/DE8007086U1/en not_active Expired
-
1981
- 1981-03-10 US US06/242,356 patent/US4397804A/en not_active Expired - Lifetime
- 1981-03-11 CA CA000372766A patent/CA1162014A/en not_active Expired
- 1981-03-12 CH CH1701/81A patent/CH651797A5/en not_active IP Right Cessation
- 1981-03-13 IT IT67346/81A patent/IT1146706B/en active
- 1981-03-13 FR FR8105104A patent/FR2477948B1/en not_active Expired
- 1981-03-13 AT AT0117181A patent/AT383987B/en not_active IP Right Cessation
- 1981-03-14 JP JP3598981A patent/JPS56146715A/en active Pending
-
1983
- 1983-02-22 US US06/468,371 patent/US4521175A/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
---|---|
FR2477948A1 (en) | 1981-09-18 |
IT1146706B (en) | 1986-11-19 |
JPS56146715A (en) | 1981-11-14 |
US4397804A (en) | 1983-08-09 |
IT8167346A0 (en) | 1981-03-13 |
ATA117181A (en) | 1987-02-15 |
AT383987B (en) | 1987-09-10 |
CH651797A5 (en) | 1985-10-15 |
DE8007086U1 (en) | 1982-03-18 |
FR2477948B1 (en) | 1985-07-12 |
US4521175A (en) | 1985-06-04 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
CA1162014A (en) | Method and apparatus for producing containers from thermoplastic sheet material | |
CA2443888C (en) | Method for preparing air channel-equipped film for use in vacuum package | |
US3014320A (en) | Method of applying shrink covers | |
US4114348A (en) | Packaging techniques for semi-rigid packages | |
US20090007524A1 (en) | Device for Producing Deep Packaging Trays Comprising a Cooled Lower Mould Section | |
US5366685A (en) | Process of molding thermoplastic sheet by plug assist vacuum forming | |
US20100287893A1 (en) | Packaging machine and method for closing containers with lids | |
EP1412161B1 (en) | Apparatus, forming means and methods for forming sheet material | |
US4168598A (en) | Vacuum packaging method and apparatus | |
US4932856A (en) | Apparatus for thermoforming hollow articles | |
US3472723A (en) | Container manufacture | |
US3828520A (en) | Vacuum packaging method and platen therefor | |
US7138025B2 (en) | Method for manufacturing a sealable bag having an integrated tray for use in vacuum packaging | |
US4137688A (en) | Method of vacuum packing objects in plastic foil | |
US20050035020A1 (en) | Sealable bag having an integrated tray for use in vacuum packaging | |
CN109562850B (en) | Packaging tool, packaging machine and method for producing a skin package | |
US5158786A (en) | Apparatus for deep drawing an open bowl | |
US3964856A (en) | Vacuum moulding techniques | |
US4219987A (en) | Method for skin packaging using platen forming of the film, and packages produced thereby | |
US3299604A (en) | Method of packaging | |
US5369937A (en) | Continuous casting and packaging | |
EP0408874B1 (en) | Process of molding thermoplastic sheet | |
US20030122287A1 (en) | Method of manufacturing packaging articles, and a corresponding manufacturing machine | |
FI76750C (en) | Packaging method and device for carrying out the procedure | |
JP2002001840A (en) | Apparatus for shaping paper-made tray |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
MKEX | Expiry |